He not only returned with his job-security angst, he also brought back his sense of humor.

For example, Costanzo was thrilled to see 49ers linebacker Dan Skuta, a fellow special-teamer he faced for two seasons in the AFC North when Costanzo was with the Browns and Skuta was with the Bengals. Part of Costanzo's excitement came from finally realizing he was 15 pounds lighter than Skuta, who weighs 250.

"I had some battles with Skuta, man," Costanzo said. "I remember thinking, 'Geez, this guy is really good.' But when I got here, I was like, 'Well, at least this guy's bigger than me.' I thought he was my same size, so it gave me some comfort knowing that he was a little bigger."

Costanzo now can count Skuta as a teammate - and part of his formidable competition. The 49ers return all eight of the players who had at least seven special-teams tackles last season when they ranked fifth in the NFL in opponent's kickoff-return average (20.4) and 13th in punt returns (8.7).

Among that group is a player such as cornerback Darryl Morris, who is younger (23) and cheaper ($495,000) than Costanzo, whose $855,000 veteran minimum salary is based on his seven years of service.

"That's the way the league is going," Costanzo said. "Teams can get a couple of younger guys for the price of an older guy. Once you get up in years, your salary gets bigger and, even if you produce, it's a lot harder to stick on teams."

Costanzo produced the past two seasons with the Bears. Last year, he collected a team-high 17 tackles after he ranked second in that category in 2012 with 11. Still, he spent three months waiting for a free-agent offer before the 49ers signed him in June.

For his part, Skuta is glad the 49ers made that call.

"Unfortunately, I had to play against Blake and he was always a thorn in my side out there," Skuta said. "I felt like anyone that gave me a hard time was a good player, so it's good we're on the same team. We didn't like each other then, but we're good now."

It sounds as if Costanzo won't be good until he secures a spot on the 53-man roster, but he insists he's not always unhappy during camp. He enjoys playing football, he explained, but not pondering his uncertain future in the sport.

"Oh, I'm not really miserable," he said. "I just pretend to be miserable. I have fun out there. It's all this other baloney I don't like."